Here are a few more questions....

Is the snake near a window?

How much are you feeding weekly?

What size prey are you feeding?

Sometimes smaller prey items go unnoticed as they grow larger. In the fall/winter as day light shortens, snake near windows, or in view of windows, will take their cues from the outside environment. This is their normal time of year to slow down and conserve energy for spring. Even without the outside stimulus, we still have changes in barometric pressure that tell them anyway. It is just their instinct. I wouldn't worry too much about it.

Brandon